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The Complete Guide to Used Car Inspection & History Checks: From Accident Detection to Critical Component Evaluation

The biggest fear when buying a used car is unknowingly purchasing a vehicle with prior accidents, flood damage, or fire damage. These cars not only pose safety risks but can also lead to exorbitant repair costs. This guide provides a systematic approach to evaluating a used car's true condition through professional inspection techniques and history checks, helping you avoid costly mistakes.

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1. How to Identify Accident/Flood/Fire-Damaged Cars

1.1 Accident Car Inspection (Focus on Structural Damage)

Inspection AreaNormal ConditionAccident IndicatorsTools/Methods
Body WeldsSmooth, uniform factory weldsRough/uneven repairsPaint meter + visual check
Door HingesNo disassembly marksScratched/displaced bolts10x magnifier
Frame RailsStraight, no creasesBondo repairs/cracked paintLift inspection
Glass DatesOlder than production dateNewer than production (replaced)Decode glass markings

Red Flags:

  • Bent frame rails (repairs cost ¥20,000+; compromise safety).

  • Airbag replacement (check for explosive residue near lighter socket).

1.2 Flood-Damaged Car Detection (More Harmful Than Accidents)

CheckpointNormalFlood Damage Signs
Seat TracksNo rustRust/mud deposits
WiringDry, no oxidationGreen corrosion/mold
Spare Tire WellCleanWater stains/mildew
VentsNo debrisClogged dust/foul smell

Deep Checks:

  • Remove door sills: Check for internal rust.

  • OBD scan: Inconsistent ECU dates signal flood repairs.

1.3 Fire-Damaged Car Identification (Highest Risk)

CheckpointNormalFire Damage Signs
WiringFlexible plasticMelted/brittle
Firewall InsulationIntactCharred/burnt odor
PaintUniformPatchy respray

Legal Risk: Fire-damaged cars may fail inspections; insurers can deny claims.


2. History Checks: Maintenance & Insurance Records

2.1 Top History Report Tools

ToolData SourceCostKey Feature
CarfaxNorth America$40/reportEssential for imports
Che300Chinese insurers/dealers¥29–99Repair details included
ChaBSNationwide dealer records¥39/reportVIN decoding
Dealer QueryBrand databasesFree/paidOwner authorization needed

What to Look For:

  • Odometer fraud (e.g., 50,000 km in 2021 → 30,000 km in 2022).

  • Major repairs (engine/transmission replacement).

2.2 Decoding Insurance Claims

  • Payout Amounts:

    • <¥10,000: Minor scratches.

    • ¥30,000+: Likely structural damage.

  • Keywords:

    • "Cut/weld" = Severe accident.

    • "Full wiring harness replacement" = Flood suspicion.


3. Critical Component Evaluation

3.1 Engine Inspection

TestHealthyProblem Signs
Cold StartSmooth RPM dropRough idle/blue-white smoke
Oil CapNo emulsionMilky residue (head gasket leak)
ExhaustClear/odorlessBlue (burning oil)/black (carbon buildup)

Pro Methods:

  • Compression test (9–12 bar normal).

  • Boroscope for cylinder scoring (vertical scratches = rebuild needed).

3.2 Transmission Check

TypeRed FlagsRepair Cost
ATRough shifting¥8,000–20,000
DCTLow-speed jerking¥3,000–6,000 (clutch)
CVTWhining/slipping¥30,000–50,000 (full replacement)

Road Test Tips:

  • Hard acceleration (30–80 km/h): Watch for delayed shifts.

  • Reverse → Drive: Listen for "clunking."

3.3 Undercarriage Assessment

PartCheck ForRisks If Failed
Control ArmsCracked bushingsMisalignment/uneven tire wear
Tie RodsTorn bootsLoose steering
DriveshaftJoint playVibration at speed

Must-Do: Lift the car; shake wheels to test bearings. Replace cracked rubber parts immediately.


4. Step-by-Step Inspection Checklist

  1. Static Inspection (30 min)

    • Paint thickness scan (factory: 80–160 μm).

    • Check seatbelt roots for moisture.

    • Inspect spare tire well drainage.

  2. Road Test (20 min)

    • Coast at 60 km/h (listen for wheel bearing noise).

    • Brake test (no pulling/squeaking).

  3. Professional Inspection (Recommended)

    • Cost: ¥300–800 (includes undercarriage report).

    • Includes:

      • Engine code scan.

      • Structural ultrasonic testing.


5. How to Avoid Scams

  • Beware "Free Transfer" traps: Verify condition before paperwork.

  • "Lady-Owned" cars: May hide aggressive driving.

  • EVs Special Notes:

    • Battery health <80% halves value.

    • OBD-check true charge cycles.

Final Advice:

  • Prioritize dealers offering 90-day buyback guarantees.

  • Demand contracts stating "no accidents/flood/fire damage."

With this guide, even beginners can avoid 90% of problem cars. Remember: A small inspection fee saves huge future losses!